40C3: tours, schedule data, tour map and calendar entries

- tour-map shortcode: Leaflet map of the tour locations with routes from the
  Congress, from the map/tours sections of data/schedule/<event>.yaml; Leaflet
  and the OSMIC, Maki and Temaki icon sets vendored; 39C3 uMap data converted.
- calendar shortcode: per tour date, a pill with an .ics download (iCalendar)
  and a Google Calendar link; Font Awesome Free vendored, fa-icon partial.
- README sections for the calendar and tour map shortcodes and the map data.

assets/vendor/icons/maki/heart.svg

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg height="15" viewBox="0 0 15 15" width="15" xmlns="http://www.w3.org/2000/svg" id="heart">
+  <path d="m13.91 7.75001c-1.17 2.24999-4.30002 5.30999-6.07002 6.93999-.1903.1718-.4797.1718-.67 0-1.78-1.63-4.91-4.69-6.08-6.93999-2.57-4.95 3.91-8.250002 6.41-3.3 2.5-4.950002 8.98002-1.65 6.41002 3.3z"/>
+</svg>